Documents disponibles écrits par cet auteur

Millisecond production of hydrogen from alternative, high hydrogen density fuels in a cocurrent multifunctional microreactor / Niket S. Kaisare in Industrial & engineering chemistry research, Vol. 48 N°4 (Février 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N°4 (Février 2009) . - pp. 1749–1760 Titre : Millisecond production of hydrogen from alternative, high hydrogen density fuels in a cocurrent multifunctional microreactor Type de document : texte imprimé Auteurs : Niket S. Kaisare, Auteur ; Georgios D. Stefanidis, Auteur ; Dionisios G. Vlachos, Auteur Année de publication : 2009 Article en page(s) : pp. 1749–1760 Note générale : Chemical enginnering Langues : Anglais (eng) Mots-clés : Pseudo-2-dimensional  model  Hydrogen  Catalytic  ammonia  Platinum Résumé : A pseudo-2-dimensional model is used for modeling a multifunctional microreactor for hydrogen generation by coupling catalytic ammonia decomposition on ruthenium with catalytic propane combustion on platinum. The two reactions are carried out in adjacent parallel plate channels in a cocurrent flow mode. Operating lines defining the attainable region are computed. The high temperatures and fast heat transfer ensure that both reactions go to completion in as low as submillisecond contact times and enable compact hydrogen production for portable and distributed power generation. The ammonia decomposition reaction tends to be limited by the intrinsic rate of reaction, whereas catalytic combustion is also affected by mass and heat diffusion. We have found that moderate and high conductivity materials are preferable because they support a rather wide attainable region. We show that one such device could enable variable hydrogen supply for variable power needs. A simple operating strategy to dial in the desirable power is proposed, which ensures high thermal efficiency (∼75% once-through efficiency of the integrated device and ∼85% reformer efficiency, both without any heat recuperation), wall isothermicity, and high conversions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800392z [article] Millisecond production of hydrogen from alternative, high hydrogen density fuels in a cocurrent multifunctional microreactor [texte imprimé] / Niket S. Kaisare, Auteur ; Georgios D. Stefanidis, Auteur ; Dionisios G. Vlachos, Auteur . - 2009 . - pp. 1749–1760. Chemical enginnering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°4 (Février 2009) . - pp. 1749–1760 Mots-clés : Pseudo-2-dimensional  model  Hydrogen  Catalytic  ammonia  Platinum Résumé : A pseudo-2-dimensional model is used for modeling a multifunctional microreactor for hydrogen generation by coupling catalytic ammonia decomposition on ruthenium with catalytic propane combustion on platinum. The two reactions are carried out in adjacent parallel plate channels in a cocurrent flow mode. Operating lines defining the attainable region are computed. The high temperatures and fast heat transfer ensure that both reactions go to completion in as low as submillisecond contact times and enable compact hydrogen production for portable and distributed power generation. The ammonia decomposition reaction tends to be limited by the intrinsic rate of reaction, whereas catalytic combustion is also affected by mass and heat diffusion. We have found that moderate and high conductivity materials are preferable because they support a rather wide attainable region. We show that one such device could enable variable hydrogen supply for variable power needs. A simple operating strategy to dial in the desirable power is proposed, which ensures high thermal efficiency (∼75% once-through efficiency of the integrated device and ∼85% reformer efficiency, both without any heat recuperation), wall isothermicity, and high conversions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800392z

Numerical analysis of fractal catalyst structuring in microreactors / Venkat Reddy Regatte in Industrial & engineering chemistry research, Vol. 50 N° 23 (Décembre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 23 (Décembre 2011) . - pp. 12925-12932 Titre : Numerical analysis of fractal catalyst structuring in microreactors Type de document : texte imprimé Auteurs : Venkat Reddy Regatte, Auteur ; Niket S. Kaisare, Auteur Année de publication : 2012 Article en page(s) : pp. 12925-12932 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Microreactor  Catalyst  Fractal  Numerical  simulation  Numerical  analysis Résumé : The objective of this work is to verify the feasibility of implementing fractal structuring to reduce the amount of active catalyst surface required in microreactors. This work follows up on the work by Phillips et al. [Chem. Eng. ScL, 2003, 58, 2403―2408], where the authors reported the use of Cantor triads to reduce the total amount of active catalyst in a mass-transfer-limited system. They considered flat-plate geometry with infinitely fast reactions. This work is extended to realistic microreactors with finite rate chemistry to study the effect of catalyst structuring in the presence of flow confinement. Fractal and periodic patterns are formed by removing the catalyst from various sections along the reactor wall, resulting in alternating catalytic and noncatalytic segments. Two-dimensional computational fluid dynamics (CFD) simulations of tubular microreactor channel with catalyst structuring are performed. Our results show that the role of catalyst structuring confined geometry is rather modest, compared to the open (flat-plate) geometries considered so far. We also show that singularities (boundary of noncatalytic and catalytic segments) formed with catalyst structuring, and not the fractal pattern itself, are responsible for improved conversion from the microreactor. Large gradients at singularities result in enhanced mass transfer, which is analyzed using Sherwood number correlations. The effect of various operating parameters is investigated. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25267450 [article] Numerical analysis of fractal catalyst structuring in microreactors [texte imprimé] / Venkat Reddy Regatte, Auteur ; Niket S. Kaisare, Auteur . - 2012 . - pp. 12925-12932. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 23 (Décembre 2011) . - pp. 12925-12932 Mots-clés : Microreactor  Catalyst  Fractal  Numerical  simulation  Numerical  analysis Résumé : The objective of this work is to verify the feasibility of implementing fractal structuring to reduce the amount of active catalyst surface required in microreactors. This work follows up on the work by Phillips et al. [Chem. Eng. ScL, 2003, 58, 2403―2408], where the authors reported the use of Cantor triads to reduce the total amount of active catalyst in a mass-transfer-limited system. They considered flat-plate geometry with infinitely fast reactions. This work is extended to realistic microreactors with finite rate chemistry to study the effect of catalyst structuring in the presence of flow confinement. Fractal and periodic patterns are formed by removing the catalyst from various sections along the reactor wall, resulting in alternating catalytic and noncatalytic segments. Two-dimensional computational fluid dynamics (CFD) simulations of tubular microreactor channel with catalyst structuring are performed. Our results show that the role of catalyst structuring confined geometry is rather modest, compared to the open (flat-plate) geometries considered so far. We also show that singularities (boundary of noncatalytic and catalytic segments) formed with catalyst structuring, and not the fractal pattern itself, are responsible for improved conversion from the microreactor. Large gradients at singularities result in enhanced mass transfer, which is analyzed using Sherwood number correlations. The effect of various operating parameters is investigated. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25267450